engine rebuild questions

Are ya having a problem with your rig? We'll try to help. Share your tech tips and experiences here. Dr. Billy Glaser, author of the "Unofficial 750 Ural Service Manual" site myural.com, is moderating this section.
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CrankyTom
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engine rebuild questions

Post by CrankyTom » Wed Jul 31, 2019 8:51 am

At 65,716 km my rear main bearing is going bad.
I know I have to replace the bearing,but I'm wondering about the crankshaft.If memory serves there are a fair number of folks that have had a rod failure at around that mark and I'm wondering about the collectives opinion on whether I should just go ahead and replace it even if it seems fine.
The cost of a new crank is a very hefty chunk of change at my house,but a rod failure on the road would be even worse.
Second question: I've started looking at the manual and the videos on replacing the crank and so far I see no mention of setting the end play on the crank - is there a procedure for that or is it all controlled by the way the crank is mounted in the bearing?Any thing else I should be looking for?
All info and help appreciated
Tom
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URALNUT60
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Re: engine rebuild questions

Post by URALNUT60 » Wed Jul 31, 2019 9:26 am

I would pull crank check for true, have rod play checked, replace both bearings, check bore and rings out, cross hatch hone if needed, relapp the valves, freshen the motor, hopefully get another 65km before serious rebuild!

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Re: engine rebuild questions

Post by gobium » Wed Jul 31, 2019 9:34 am

Tom
Bite the bullet and install new D10 crankshaft.
I dont show the whole world how to install crankshaft, not my job
but I willing to walk you through the process on phone.
Very easy but you got to do it correctly without using BFH.

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Re: engine rebuild questions

Post by CrankyTom » Wed Jul 31, 2019 9:51 am

gobium wrote:
Wed Jul 31, 2019 9:34 am
Tom
Bite the bullet and install new D10 crankshaft.
I dont show the whole world how to install crankshaft, not my job
but I willing to walk you through the process on phone.
Very easy but you got to do it correctly without using BFH.
Thanks Van,I've watched yours and Billy G's videos and it looks simple enough(relatively speaking).It will be a while yet before I get to that point (I havent even started to tear into the motor yet) and I hate to bother you if it's not necessary but if I get stuck I'll give you a shout.
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Re: engine rebuild questions

Post by gobium » Wed Jul 31, 2019 9:52 am

If bad front main bearing replace the crankshaft , hint you got to pull crankshaft.
If bad main rear bearing, keep crankshaft, you dont to pull engine to do that repair.

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Re: engine rebuild questions

Post by CrankyTom » Wed Jul 31, 2019 9:54 am

URALNUT60 wrote:
Wed Jul 31, 2019 9:26 am
I would pull crank check for true, have rod play checked, replace both bearings, check bore and rings out, cross hatch hone if needed, relapp the valves, freshen the motor, hopefully get another 65km before serious rebuild!
Thanks,I was thinking pretty much along the same lines - if it wasn't for the cost replacing the crank would seem to be a no brainer as long as I'm that far into the engine.
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Re: engine rebuild questions

Post by CrankyTom » Wed Jul 31, 2019 9:57 am

gobium wrote:
Wed Jul 31, 2019 9:52 am
If bad front main bearing replace the crankshaft , hint you got to pull crankshaft.
If bad main rear bearing, keep crankshaft, you dont to pull engine to do that repair.
Thanks again Van,the noise seems to indicate a rear bearing but I won't know for sure until I get a chance to actually look.
I'll pull the cylinders and check the rods any way just to be sure.
Last edited by CrankyTom on Wed Jul 31, 2019 9:59 am, edited 1 time in total.
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Re: engine rebuild questions

Post by jaybird » Wed Jul 31, 2019 9:58 am

How did you determine that the rear main bearing is going bad?
If the engine is performing well otherwise, "I" would probably just replace the bearing and the rear seal, and go back to riding.
There's nothing special about 65k Kilos (Except that your rig/engine made it that far) in regard to big end bearing failure, they go when they go.
I had the rear main bearing fail in my 2005 GearUp, I was able to replace it with the engine in the frame, I was back on the road in a day.
Why make a mountain out of a molehill?
Good luck.

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Jaybird
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1995 Olive Tourist
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Re: engine rebuild questions

Post by CrankyTom » Wed Jul 31, 2019 10:07 am

jaybird wrote:
Wed Jul 31, 2019 9:58 am
How did you determine that the rear main bearing is going bad?
If the engine is performing well otherwise, "I" would probably just replace the bearing and the rear seal, and go back to riding.
There's nothing special about 65k Kilos (Except that your rig/engine made it that far) in regard to big end bearing failure, they go when they go.
I had the rear main bearing fail in my 2005 GearUp, I was able to replace it with the engine in the frame, I was back on the road in a day.
Why make a mountain out of a molehill?
Good luck.

Happy trails,
Jaybird
Where the noise is coming from,the fact it goes away when you pull the clutch in,the type of noise itself and a
couple of my pals who used to ride beemers say the same.
I won't know for sure until I actually dig into the engine,I'm just trying to consider all possible scenarios in advance so I can finish the job as fast as possible once I get started without having to stop and do research in the middle or find out later I should have done more.
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Re: engine rebuild questions

Post by jaybird » Wed Jul 31, 2019 10:54 am

CrankyTom wrote:
Wed Jul 31, 2019 10:07 am
jaybird wrote:
Wed Jul 31, 2019 9:58 am
How did you determine that the rear main bearing is going bad?
If the engine is performing well otherwise, "I" would probably just replace the bearing and the rear seal, and go back to riding.
There's nothing special about 65k Kilos (Except that your rig/engine made it that far) in regard to big end bearing failure, they go when they go.
I had the rear main bearing fail in my 2005 GearUp, I was able to replace it with the engine in the frame, I was back on the road in a day.
Why make a mountain out of a molehill?
Good luck.

Happy trails,
Jaybird
Where the noise is coming from,the fact it goes away when you pull the clutch in,the type of noise itself and a
couple of my pals who used to ride beemers say the same.
I won't know for sure until I actually dig into the engine,I'm just trying to consider all possible scenarios in advance so I can finish the job as fast as possible once I get started without having to stop and do research in the middle or find out later I should have done more.
When the rear main bearing went on my GearUp it started out as a low growl and a slight vibration.
Your current crankshaft could last two more Kilometers or another 65K, I put a used crankshaft, with unknown kilos on it in my GearUp in 2010 just to make a trip up Mount Washington, it's still in there, and that rig has a hard life.
If rebuilding your engine makes you feel better and instills confidence in your rig, then that may be the way you want to go, but it's not the only way.
If you put a lot of Kilos on your rig then a crankshaft replacement/engine rebuild is inevitable at some point, weather you do it preemptively is your choice.
Good luck and beware of Hucksters.

Happy trails,
Jaybird
2005 Gear-Up, Mr. Nat_ural 108,000+ Kilometers and counting
2013 Retro, Black beauty, AKA Lucky "13"
1995 Olive Tourist
1975 Enfield Diesel Bullet
2008 Enfield Bullet 500
1974 BMW R 75/6
Etc.

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Re: engine rebuild questions

Post by RC20 » Wed Jul 31, 2019 2:12 pm

Get as much data as you can from pulling the cylinders and seeing what is up with the rear.

If it looks ok otherwise, replace the rear bearing (assuming that is the cause)

If something else then occurs, then pull the engine and rebuild the whole thing.

Over the years its been about 50/50 in fixing whats is in front of you and fine for a long time after vs you fix the oblivious thing and then other stuff is going wrong as the first thing was just what showed up first.
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Re: engine rebuild questions

Post by Msblu79 » Wed Jul 31, 2019 2:29 pm

Maybe the crank is OK and you might get lucky and find that the noises are from something else like the clutch assembly. If yours is still the original clutch it may be ready for replacement. :)
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Re: engine rebuild questions

Post by Wildhorse Cafe » Wed Jul 31, 2019 3:06 pm

Having a hydrolic panini press is a must for reassembly.
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Re: engine rebuild questions

Post by gobium » Wed Jul 31, 2019 3:49 pm

Wildhorse Cafe wrote:
Wed Jul 31, 2019 3:06 pm
Having a hydrolic panini press is a must for reassembly.
No press needed for crankshaft installation.
Sergie done it for 45 years.
At factory they use press but their shim the crankshaft cheeks
You are using Ski method

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Re: engine rebuild questions

Post by jaybird » Wed Jul 31, 2019 3:56 pm

Wildhorse Cafe wrote:
Wed Jul 31, 2019 3:06 pm
Having a hydrolic panini press is a must for reassembly.
:D It's a big job, you might get hungry part way through.

Happy trails,
Jaybird
2005 Gear-Up, Mr. Nat_ural 108,000+ Kilometers and counting
2013 Retro, Black beauty, AKA Lucky "13"
1995 Olive Tourist
1975 Enfield Diesel Bullet
2008 Enfield Bullet 500
1974 BMW R 75/6
Etc.

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